Potassium iodide: When to take "radiation pills"

Potassium iodide pills on the shelf of a Plano, Texas drugstore on March 15, 2011.

AP

(CBS) Potassium iodide pills are suddenly a hot commodity.

Americans snapping up bottles of the cancer-preventing salt even though the U.S. government has said that radiation leaking from Japan's earthquake-stricken nuclear reactors poses little if any threat to the U.S., as CBS has reported.

Potassium iodide, whose chemical name is KI, doesn't work for all forms of cancer associated with exposure to radiation. But it can help lower the risk for thyroid cancer in people who have ingested or inhaled radioactive forms of iodine. a.k.a. radioiodones. It does that by flooding the thyroid with non-radioactive iodine, thereby limiting the gland's absorption of radioiodones.

KI works if taken within three to four hours of exposure and should be taken on a daily basis until the threat passes, according to the FDA. Though it's available over the counter, it's smart to consult a doctor before taking it and - perhaps most important - whether it makes sense to take it at all.